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Silvia Viciani

Publications and source records attributed to Silvia Viciani.

5 recordsLinked to original sources

Disorder and dephasing as control knobs for light transport in optical fiber cavity networks

Transport phenomena represent a very interdisciplinary topic with applications in many fields of science, such as physics, chemistry, and biology. In this context, the possibility to design a perfectly controllable experimental setup, where to tune and optimize its dynamics parameters, is a challenging but very relevant task to emulate, for instance, the transmission of energy in light harvesting processes. Here, we experimentally build a scalable and controllable transport emulator based on optical fiber cavity networks where the system noise parameters can be finely tuned while maximizing the transfer efficiency. In particular, we demonstrate that disorder and dephasing noise are two control knobs allowing one to play with constructive and destructive interference to optimize the transport paths towards an exit site. These optical setups, on one side, mimic the transport dynamics in natural photosynthetic organisms and, on the other, are very promising platforms to artificially design optimal nanoscale structures for novel, more efficient, clean energy technologies.

quant-ph↗

Observation of noise-assisted transport in an all-optical cavity-based network

Recent theoretical and experimental efforts have shown the remarkable and counter-intuitive role of noise in enhancing the transport efficiency of complex systems. Here, we realize simple, scalable, and controllable optical fiber cavity networks that allow us to analyze the performance of transport networks for different conditions of interference, dephasing and disorder. In particular, we experimentally demonstrate that the transport efficiency reaches a maximum when varying the external dephasing noise, i.e. a bell-like shape behavior that had been predicted only theoretically. These optical platforms are very promising simulators of quantum transport phenomena, and could be used, in particular, to design and test optimal topologies of artificial light-harvesting structures for future solar energy technologies.

quant-ph↗

Single-photon excitation of a coherent state: catching the elementary step of stimulated light emission

When a single quantum of electromagnetic field excitation is added to the same spatio-temporal mode of a coherent state, a new field state is generated that exhibits intermediate properties between those of the two parents. Such a single-photon-added coherent state is obtained by the action of the photon creation operator on a coherent state and can thus be regarded as the result of the most elementary excitation process of a classical light field. Here we present and describe in depth the experimental realization of such states and their complete analysis by means of a novel ultrafast, time-domain, quantum homodyne tomography technique clearly revealing their non-classical character.

quant-ph↗

Recurrent fourth-order interference dips and peaks with a comb-like two-photon entangled state

We demonstrate full selective control over the constructive or destructive character of fourth-order recurring interferences in a modified version of a HOM interferometer using comb-like two-photon states. The comb spectral/temporal structure is obtained by inserting an etalon cavity in the signal path of an entangled photon pair obtained by pulsed spontaneous parametric down-conversion. Both a simple qualitative discussion and a complete theoretical derivation are used to explain and analyze the experimental data.

quant-ph↗

Tomographic reconstruction of the single-photon Fock state by high-frequency homodyne detection

A single-photon Fock state has been generated by means of conditional preparation from a two-photon state emitted in the process of spontaneous parametric down-conversion. A recently developed high-frequency homodyne tomography technique has been used to completely characterize the Fock state by means of a pulse-to-pulse analysis of the detectors' difference photocurrent. The density matrix elements of the generated state have been retrieved with a final detection efficiency of about 57%. A comparison has been performed between the phase-averaged tomographic reconstructions of the Wigner function as obtained from the measured density-matrix elements and from a direct Abel transform of the homodyne data. The ability of our system to work at the full repetition rate of the pulsed laser (82 MHz) substantially simplifies the detection scheme, allowing for more ``exotic'' quantum states to be generated and analyzed.

quant-ph↗